“…Previous studies have suggested that mitral valve disease is found in 2.2% of hospital necropsies on patients aged 60 years and over (Hammond and Platts, 1960) and in 3-1 % of hospital necropsies on patients aged 50 years and over (Hargreaves, 1961). In the former series 30% were undiagnosed, but in the latter less than 5%.…”